Effects of full moon and no moon on the birth of male and female offsprings were studied in Indian Couples of the age group 20 to 40 years. It was observed that 42 wives who were conceived within 24 hours of ovulation at full moon gave birth of 40 male and 2 female babies. On the other hand 40 women conceived on the day of ovulation 3 days prior to full moon gave birth of 13 male and 27 female babies. But only 5 women conceived on no moon, all of them gave birth of female babies. It was also observed that vaginal pH of the ovulated women during full moon was alkaline (pH 8.7 +/- 0.4) while pH was weak acidic in women ovulated 3 days prior to full moon and no moon (pH 6.4 +/- 0.5; 6.2 +/- 0.5). The basal body temperature (BBT) was increased 0.7 degrees F to 1.3 degrees F during the ovulation period when compared with women during the absence of ovulation. But there is an increase in temperature 0.5 degrees F more in women ovulated in full moon than no moon. Together, these results indicate that alkaline vaginal fluid medium and more rise of BBT during full moon favour conception of male [corrected] babies. This method gives the couple more chance of having male child if conception occurs in the day of ovulation in full moon and having female child if conception occurs in no moon.